DESCRIPTION: (Adapted from the application abstract) A better understanding of the pathogenesis of AIDS will facilitate drug and vaccine development. Recent data have shown that large amounts of HIV-1 are produced and destroyed each day. Antiviral drugs have been able to greatly reduce the level of virus replication, and the steady state viral burden, until resistant variants emerge to return virus burdens to pre-drug levels. Replication competent, nonpathogenic deletion mutants of SIV have provided solid vaccine protection against challenge by pathogenic virus. Viral and/or host factors may contribute to long-term nonprogression in rare HIV-1 infected individual. Despite these and other advances on a variety of fronts, scientist do not adequately understand the basic mechanisms by which HIV is able to continue to replicate in the face of an apparently strong host immune response. They have not adequately learned how to combat the insidious ability of SIV and HIV to mutate, to tolerate mutations, and to use mutant forms to the advancement of the virus and the detriment of the host. The immunological mechanisms responsible for protection induced by live attenuated deletion mutants or in long-term nonprogressing survivors is unclear. The goal of the meeting is to bring together the leading experts in the field of AIDS pathogenesis to present their latest results that bear on these problems.